Rubber Ride Torsion (no springs)
Conventional Leaf Spring (either straight or dropped)

The Three Basic Sizes:

Typical Rating	Axle tube OD Size (spring axle only)	Spindle Number (see chart below)	Outer Bearing ID Size	Inner Bearing ID Size	Seal ID Size	Brake drum Size (Bolt pattern) (See chart below)	Dust cap ID Size
2000#-2200#	1.75"	BT8 or BTR	1.000" (L44643) 1.063" (L44649)	Same as Outer Bearing	1.25" (12192TB) or 1.50" (10-60)	7" (4x4 or 4x4.5)	1.78 or 1.98"
3500#	2.375"	#84	1.063" (L44649)	1.375"(L68149)	1.75" (10-19)***	10" 5 Lug (4.5"/4.75"/ 5.0"/5.5")+(6x5.5")	1.98"
5200#-7000#	3.00"	#42	1.25" (15123) (LD)* 1.25" (14125A) (HD)	1.75" ( 25580)	2.125 (10-10)* 2.250  (10-36)	12" (6x5.5" or 8x6.5")	2.44" or 2.71"

As you can see, there are only 3 basic sizes of axles:





With 4, 6 and 8 bolt Wheels, just measure across to the opposite lug to get the bolt circle.
On 5 bolt wheels, you must use the chart below to figure your bolt circle:



How to measure your axle, (to order a replacement)



* Notes:

• There are many other less common axles out there, this covers "Most" axles 7000# and lighter
• Mobile home axles may or may not use standard parts, you have to look inside yourself.
• The large #42 spindle can have either 2.25 or 2.125 ID seals, you have to check.
• Not all axles have brakes, but the bearing sizes are still the same, either brake or idler.
• Rarely, I have seen a LM67048 Outer bearing used on the #42 spindle (light duty)
  

*** on Some Square Tube axles, found almost always on Boat Trailers (EZ Loader, Ranger, etc) Made by UFP, the grease seal will be slightly smaller ID of 1.68".  If you have a boat trailer with a square tube axle, check your seal size before ordering.